Height recording systems using an optical level and a graduated telescopic rule held by a second observer are known.
Systems using laser scanning on a photosensitive mast to determine a height are also known. This type of device is described in U.S. Pat. No. 5,812,721 that requires a photosensitive mast comprising a plurality of photosensitive elements arranged around the mast. This device has the disadvantage of either using a very long mast fitted with large numbers of photosensitive elements and therefore expensive, or having a mast limited in size with a small number of photosensitive sensors to reduce the price of the mast, and in this case it is impossible to measure all values of height or level difference. One example of a telescopic rule is described in document U.S. Pat. No. 6,076,267.
Therefore, the purpose of this invention is to overcome one or several disadvantages according to prior art by defining a simple device comprising few photosensitive sensors capable of efficiently and quickly measuring values of height or level difference.